Python(Pygame) - 对象实例以不同的速度移动到背景

Question

这已经在我的头上已经好几天了。我正在尝试创建一个游戏，其中固定在中间的玩家，并且基于瓷砖的背景在玩家移动时会流畅地在玩家后面移动并生成其他瓷砖图像。到目前为止，背景的效果很好。

当我尝试将对象添加到背景（例如一棵树）时，就会出现问题。我希望这个对象保持固定在某个背景位置，但是随着玩家的移动，该对象与背景逐渐移动。也就是说，该对象会随着玩家的移动而移动（如它应该），但是它会移动 to

。

我已经将原因隔离到了世界。如果您删除了整个IF/Elif部分，则行为看起来不错（当然背景不正确更新，因此我们需要本节）。不知何故，随着TileShift跳过，屏幕上的每个对象也会跳过几个像素。在花费了一周多的研究和实验之后，我仍然无法修复它。我尝试更改图像，更改tileShift截止点，更改调用更新/绘制方法的顺序等。

请参阅下面的（从原始但独立的）代码（大量剥离）。请注意，我们需要一个带有图案的背景图像（请参阅世界一流的初始化），否则您将无法看到我所描述的行为，因为错误的运动是如此逐渐。为了获得最佳性能，请使用70x70 PNG图像。

希望这种解释是有道理的，请让我知道是否需要任何其他信息。任何帮助将不胜感激！

import pygame
# Initialisation
SCREEN_WIDTH, SCREEN_HEIGHT = 800, 850
pygame.init() # Initialise pygame
window = pygame.display.set_mode((SCREEN_WIDTH, SCREEN_HEIGHT)) # Set the window surface (the main screen of the game)
pygame.display.set_caption("Game") # Game window caption
window_rect = window.get_rect()
# GLOBAL VARIABLES
WorldMove = dict(x=0, y=0) # List for the direction and amount the background moves as the player moves
PlayerMoveSpeed = 5
# CLASSES
class World(pygame.sprite.Sprite):
    def __init__(self):
        self.tileShift = dict(x=0, y=0)  # Tracker for when the player has passed from one map tile to another
        # Load and set up the tile images
        self.tiles = pygame.image.load("ImagesTilesTile.png")
        self.tileSize = self.tiles.get_rect().size[0] # Assumes a square size
        self.map = pygame.Surface((self.tileSize*14,self.tileSize*15)) # Visible area surface size, based on tile size
        self.rect = self.map.get_rect() # Create a rect attribute for the World, so it can be blitted to the window
        self.rect.x, self.rect.y = -self.tileSize,-self.tileSize # The map is blitted starting one tile size above left of the screen (so we see no whitespace)
    def update(self):
        # Move the map around the player based on WorldMove, which is set in the player_move function
        self.rect.x += WorldMove["x"]
        self.rect.y += WorldMove["y"]
        # Update the tileShift based on player movement so we know when they've moved onto another tile
        if WorldMove["x"] != 0: self.tileShift["x"] -= WorldMove["x"]
        if WorldMove["y"] != 0: self.tileShift["y"] -= WorldMove["y"]
        # Once the self.tileShift has passed the size of one of the tile images, reset it and move self.matrix by 1
        if self.tileShift["x"] < -self.tileSize:
            self.tileShift["x"] = 0 # Reset the tileShift variable
            self.rect.x = -self.tileSize # Reset the point from which the map is blitted to window to top left of visible screen
        elif self.tileShift["x"] > self.tileSize:
            self.tileShift["x"] = 0
            self.rect.x = -self.tileSize
        if self.tileShift["y"] > self.tileSize:
            self.tileShift["y"] = 0
            self.rect.y = -self.tileSize
        elif self.tileShift["y"] < -self.tileSize:
            self.tileShift["y"] = 0
            self.rect.y = -self.tileSize
    def draw(self):
        # Draw the tiles in a grid in the visible area
        for y in range(15): # Visible number of tiles on y axis
            for x in range(14): # Visible number of tiles on x axis
                self.map.blit(self.tiles, (self.tileSize*x, self.tileSize*y)) # Blit each tile onto self.map
        window.blit(self.map, self.rect) # Blit self.map onto the window
class Player(pygame.sprite.Sprite):
    def __init__(self):
        self.image = pygame.Surface((35, 35))
        self.image.fill((0, 0, 0))
        self.rect = (SCREEN_WIDTH/2, SCREEN_HEIGHT/2) # Player is always in middle of screen
    def player_move(self):
        global WorldMove # Make sure that we're referring to and updating the global variable for the world movement
        key = pygame.key.get_pressed()
        x, y = 0, 0
        if key[pygame.K_w] or key[pygame.K_UP]: y = PlayerMoveSpeed
        if key[pygame.K_d] or key[pygame.K_RIGHT]: x = -PlayerMoveSpeed
        if key[pygame.K_a] or key[pygame.K_LEFT]: x = PlayerMoveSpeed
        if key[pygame.K_s] or key[pygame.K_DOWN]: y = -PlayerMoveSpeed
        if x != 0 and y != 0: # If more than one key pressed, move diagonally
            WorldMove["x"] = int(x / 1.5)
            WorldMove["y"] = int(y / 1.5)
        else:
            WorldMove["x"] = x
            WorldMove["y"] = y
    def draw(self):
        window.blit(self.image, self.rect)
class Object(pygame.sprite.Sprite):
    def __init__(self):
        self.image = pygame.Surface((50,100))
        self.image.fill((50,50,250))
        self.rect = self.image.get_rect()
        self.rect.center = window_rect.center
        self.rect.x, self.rect.y = 100, 100 # Spawn location of the object
    def update(self): # Move the object as the world moves around the player
        self.rect.x += WorldMove["x"]
        self.rect.y += WorldMove["y"]
    def draw(self): # Blit the object onto the screen at its location
        window.blit(self.image, self.rect)
# Set Objects
world = World()
object = Object()
player = Player()
# Main Loop
gameRunning = True
while gameRunning:
    # Player events
    for event in pygame.event.get():
        if event.type == pygame.QUIT or (event.type == pygame.KEYDOWN and event.key == pygame.K_ESCAPE):
            gameRunning = False
        player.player_move() # Move player based on movement key(s) pressed (if any)
    # Class updates and drawing to the screen
    window.fill((255, 255, 255)) # Fill the window with background white
    world.update()
    world.draw()
    object.update()
    object.draw()
    player.draw()
    pygame.display.update() # Refresh the display
# End - only reaches this point if gameRunning = False
pygame.quit()

Answer 1

，而不是将World实例的self.rect设置为 -self.tileSize，in-或降低rect属性和 self.tileShift，由 self.tileSize：

if self.tileShift["x"] < -self.tileSize:
    self.tileShift["x"] += self.tileSize
    self.rect.x -= self.tileSize
elif self.tileShift["x"] > self.tileSize:
    self.tileShift["x"] -= self.tileSize
    self.rect.x += self.tileSize
if self.tileShift["y"] > self.tileSize:
    self.tileShift["y"] -= self.tileSize
    self.rect.y += self.tileSize
elif self.tileShift["y"] < -self.tileSize:
    self.tileShift["y"] += self.tileSize
    self.rect.y -= self.tileSize